Postherpetic neuralgia (PHN) is a common complication of herpes zoster. As a kind of continuous acupuncture, indwelling trocar therapy (ITT) involves inserting a trocar into the skin and retaining the soft cannula in the body for 24 h. However, the efficacy and safety of ITT on PHN require further verification. In this study, the medical records of 122 patients with PHN were retrospectively analyzed. Patients were divided into the control group (patients who received conventional drug therapy) and the ITT group (patients who underwent ITT combined with conventional drug therapy). The Visual Analog Scale (VAS), Quality of Sleep (QS), 36-Item Short Form Health Survey (SF-36), dosage of drug and adverse events were analyzed at days 1, 3, 7, 14, 28, 90, and 180 after treatment. The total efficiency rate (TER) was analyzed after 6 months of follow-up. The VAS, QS and SF-36 scores in the ITT group improved substantially compared with those in the control group after 6 months of follow-up (p < 0.001). The average dosage of anticonvulsants and analgesics decreased significantly in the ITT group (p < 0.001). The TER in the control group was 52.46%, compared with 73.77% in the ITT group (p < 0.05). There were no adverse events, such as bleeding and infection, observed in the ITT group. For PHN patients, the combination of ITT and medicine therapy reduced VAS, improved quality of life, increased the efficiency rate, remarkably reduced the dosage of traditional medicine, and had no significant side effects. In addition, ITT was more effective in patients with a short duration of PHN than in chronic PHN patients.